Method And Apparatus For Support Removal Using Directed Atomized And Semi-Atomized Fluid

ABSTRACT

An apparatus and method for removing support material from and/or smoothing surfaces of an additively manufactured part (the “AM part”) is disclosed. The apparatus may include a chamber, a support surface within the chamber, and one or more nozzles within the chamber. The nozzles may be the same size or different sizes. The support surface may be configured to support the AM part. The support surface may have one or more openings sized and configured to allow the fluid to pass through the opening(s). The nozzles may be configured to spray a fluid at the AM part, and the spray may be an atomized or semi-atomized spray of the fluid.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. provisionalpatent application Ser. No. 62/612,483, filed on Dec. 31, 2017, theentire disclosure of which is herein incorporated by this reference.

FIELD OF THE INVENTION

This invention relates generally to a method and apparatus for removingsupport material from parts that have been made via additivemanufacturing techniques, such as 3D printing.

BACKGROUND OF THE INVENTION

Additive manufacturing processes, such as 3D printing (e.g. SelectiveLaser Sintering (SLS), Stereolithography (SLA), fused depositionmodeling (FDM), material jetting (MJ), electron beam (e-beam), etc.)have enabled the production of parts having complex geometries thatwould never be possible through traditional manufacturing techniques,such as casting, injection molding, or forging. However, additivemanufacturing produces parts that require significant efforts to removeunwanted support material. The support material is needed during themanufacturing process to support portions of the part as the part isbeing manufactured in order to achieve complex geometries. After themanufacturing process is completed, the unwanted support material mustbe removed and/or rough surfaces may need to be smoothed.

The support material itself can have a complex geometry and can also beextensive. Additionally, since additive manufacturing manufactures apart in discrete layers, the surface of a part is often rough, becauseadjacent layers may not end in similar locations thereby leaving a roughbumpy outer surface. Such a rough outer surface is unappealing from avisual standpoint, and the uneven surface can create stressconcentrations, which could develop during testing or use of the partand lead to pre-mature failure.

A current option in the additive manufacturing industry is to manuallyremove the support material and manually finish the surface of a part inorder to produce a smooth exterior surface of the part. Depending on thetype of part, using manual labor could be cost prohibitive, and couldlead to excessive removal of material, an uneven surface, or both. If asurface is finished unevenly or incompletely, stress concentrationscould still be unintentionally prevalent, leading to pre-mature failureof the part. In addition, manual removal of unwanted support materialand manual surface finishing lacks consistency over an extended periodof time and from part to part. And, such manual removal/finishing maycreate a bottleneck in the production process since, for example, onetechnician can remove support material from only a single part at atime.

Another option the additive manufacturing industry is moving toward isto use a machine, such as those providing a chemical bath, to removesupport material and/or to perform surface finishing. However, suchmachines are limited in the type of process parameters that can bealtered to tailor the process to a specific part, and also such machinesrequire the attention of, and operation by, a technician while themachine is running, which does not completely eliminate the bottleneckissue described above. Additionally, if a technician is unaware that amachine is not set at the proper parameters, excessive material removalcould occur, ruining the part.

Thus, there is a need for a method and apparatus for automaticallyremoving support material from and smoothing the surface of parts madevia additive manufacturing techniques without damaging the part itself.One such approach is to use embodiments of the present invention, whichuse atomized and semi-atomized fluid, chemical dissolution, andpressurized fluid. Additionally, embodiments of the present inventionmay provide an alternative that seeks to remove the manual laborbottleneck of processing additive manufactured parts in order to achievesurface finishing and/or support removal (“SF/SR”).

SUMMARY OF THE INVENTION

The invention may be embodied as an apparatus for removing supportmaterial from and/or smoothing surfaces of an additively manufacturedpart (the “AM part”). The apparatus may include a chamber, a supportsurface within the chamber, and one or more nozzles within the chamber.The nozzles may be the same size or different sizes.

The support surface may be configured to support the AM part. Thesupport surface may have one or more openings sized and configured toallow the fluid to pass through the opening(s). For example, the supportsurface may be a screen-like surface.

The nozzles may be configured to spray a fluid at the AM part, and thespray may be an atomized or semi-atomized spray of the fluid. Thenozzles may be arranged in groups, each group being part of a sprayheader that is fed from a common supply tube. The nozzles of aparticular spray-header may be the same size, but they need not be thesame size. For example, the nozzles of a particular spray-header may beselected from two or more sizes.

The nozzles of one spray-header may be the same size as the nozzles ofanother spray-header, but the nozzles of one spray-header may bedifferently sized from the nozzles of another spray-header. For example,with regard to two spray-headers the nozzles of one spray-header may beselected to be of a first size, and the nozzles of the otherspray-header may be selected to be of a second size.

In one embodiment of the invention, there are two spray-headers ofnozzles; one above the support surface (a.k.a. “top spray-header) andone below the support surface (a.k.a. “bottom spray-header”). The topspray-header may point the nozzles to spray downward toward the AM part,and the bottom spray-header may point the nozzles to spray upward towardthe AM part.

One or more valves may be included in the apparatus so that fluid canflow and spray through a first set of nozzles having one size at thesame time that fluid cannot flow to spray through second nozzles of asecond size. For example, nozzles of a particular spray-header may be oftwo or more sizes, and fluid can be made to flow through and to sprayfrom first nozzles of one size at the same time that fluid cannot flowto spray through second nozzles of another size.

One or more of the spray-headers of nozzles may be secured to a mountthat is adjustable to move the spray-header(s) nearer to or further awayfrom the support surface. One or more of the spray-headers of nozzlesmay be connected directly or indirectly to an actuator for translatingthe spray-header(s) back and forth in a planar motion.

The apparatus may also include a tank configured to hold a volume of thefluid, and the tank may be positioned (e.g. in the chamber) to capturethe fluid after the fluid is sprayed.

The apparatus may also include a heater for heating the fluid to adesired temperature. The heater may be at least partially within thetank.

The apparatus may include a ventilation system. The ventilation systemmay be a blower for forcing air into or pulling air out of the chamber.The ventilation system may be a vent for allowing air to leave or enterthe chamber. The ventilation system may include both such a blower andsuch a vent.

The invention may be embodied as a method of removing support materialfrom and/or smoothing surfaces of an AM part. Such a method may includeproviding a chamber, a support surface within the chamber, and one ormore nozzles within the chamber. An AM part may be placed on the supportsurface, and a fluid may be sprayed at the AM part. The nozzles maygenerate an atomized or semi-atomized spray of the fluid.

The nozzles may spray at the same velocity. However, in at least oneembodiment of a method according to the invention at least one of thenozzles sprays the fluid at a velocity that is different from the sprayvelocity created by a different one of the nozzles.

The method may be carried out so that one (or more) of the nozzlessprays the fluid at a first flow rate and one (or more) of the nozzlessprays the fluid at a second flow rate. For example, in one embodimentof a method that is in keeping with the invention a first one (or more)of nozzles sprays the fluid at a first flow rate and a second one (ormore) of the nozzles sprays the fluid at a second flow rate.

The method may be carried out in such a manner that a one (or more) ofthe nozzles has a first size and one or more of the nozzles has a secondsize, and a pressure at which the fluid is supplied to the nozzles ofthe first size is different than a pressure at which the fluid issupplied to the nozzles of the second size.

A tank may be provided. The tank may be configured to hold a volume ofthe fluid, and to capture the fluid in the tank after the fluid issprayed. Such a tank may be well suited to facilitating a cycling of thefluid through the nozzles so that the same fluid may be sprayed manytimes at the AM part.

A heater may be provided, and may be arranged in the tank. The heatermay be used to heat the fluid to a desired temperature. The temperatureof the fluid may be increased toward the desired temperature while theAM part is sprayed.

Spraying of the fluid may occur from a first set of the nozzles that isconfigured to spray the fluid substantially downward toward the AM part,and also from a second set of the nozzles that is configured to spraythe fluid substantially upward toward the AM part.

While spraying occurs, the nozzles may be translated. For example, oneor more sets of the nozzles may be translated during spraying of thefluid.

Air may be blown into or pulled out of the chamber. This may be doneduring spraying and/or after spraying.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention,reference should be made to the accompanying drawings and the subsequentdescription. Briefly:

FIG. 1 is a schematic depiction of an apparatus that is in keeping withthe invention;

FIG. 2 is a schematic depiction of an additively manufactured part;

FIG. 3A is a front view of an apparatus that is in keeping with theinvention;

FIG. 3B is a side view of the apparatus depicted in FIG. 3A;

FIG. 3C is a top view of the apparatus depicted in FIG. 3A;

FIG. 4 is a schematic depiction of an apparatus that is in keeping withthe invention;

FIG. 5 is a schematic depiction of an apparatus that is in keeping withthe invention; and

FIG. 6 is a flow diagram depicting a method that is in keeping with theinvention.

DETAILED DESCRIPTION OF THE INVENTION

At the outset, it should be appreciated that like drawing numbers ondifferent drawing views identify identical, or functionally similar,structural elements of the invention.

Furthermore, it is understood that this invention is not limited to theparticular methodology, materials, or modifications described and, assuch, the invention may vary from that which is disclosed herein. It isalso understood that the terminology used herein is for the purpose ofdescribing particular aspects, and this invention is not limited to thedisclosed aspects.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention pertains. It should be understood thatmethods, devices or materials similar or equivalent to those describedherein can be used in the practice or testing of the method andapparatus.

Furthermore, as used herein, “and/or” is intended to mean a grammaticalconjunction used to indicate that one or more of the elements orconditions recited may be included or occur. For example, a devicecomprising a first element, a second element and/or a third element, isintended to be construed as any one of the following structuralarrangements: a device comprising a first element; a device comprising asecond element; a device comprising a third element; a device comprisinga first element and a second element; a device comprising a firstelement and a third element; a device comprising a first element, asecond element and a third element; or, a device comprising a secondelement and a third element.

Adverting now to the figures, with specific reference in FIGS. 1-2, thepresent invention may be embodied as a method or an apparatus 8 forSF/SR. In such a method or apparatus 8, one or more additivemanufactured parts 10 needing SF/SR are placed on a platform or tray 13in a chamber 16 of an apparatus 8 for carrying out SF/SR. An SF/SR fluid22 for dissolving and/or eroding the support material 28 may be sprayedat the part(s) 10 through nozzles 25 situated underneath the part(s) 10or above the part(s) 10 or both. The nozzles 25 below the part(s) 10 andthe nozzles 25 above the part(s) 10 may be referred herein as bottomnozzles 25B and top nozzles 25A, respectively. The fluid 22 may besupplied from a tank 31, open at its upper side. The tank 31 may besituated below the bottom nozzles 25. A pump 33 may be used to drawfluid 22 from the tank 31 and then force the fluid 22 through a seriesof pipes 50 connected to the nozzles 25, which causes the fluid 22 tospray out of the nozzles 25 at the part(s) 10. Each nozzle 25 maycomprise a pipe or tube section having multiple apertures or nozzlesthrough which the fluid 22 sprays, and these arrangements are sometimesreferenced herein, as a “spray-header”. The fluid 22 then collects backinto the tank 31 where the fluid 22 is recycled back through theapparatus, i.e., drawn from the tank 31, forced to the nozzles 25,sprayed at the parts 10, and collected in the tank 31. In this mode ofoperation the apparatus 8 may be a closed-loop system.

Additive manufactured parts 10 may be made using numerous differentmethods, classes of materials (e.g., plastics, metals), specific buildmaterials (e.g., nylon within the plastics class, aluminum within themetals class) and support materials. Each method, class of material, andspecific build material can have its own unique qualities andcharacteristics and thus may require different parameters for effectiveand efficient removal of support material 28. Additionally, for a giventype, parts 10 made by such an additive manufacturing process and/ormaterials may have very different geometries, including designs havingmore delicate features than others, which thus may require adjustmentsfor effective and efficient removal of support material 28. As explainedin more detail herein, the amount of fluid 22 sprayed, the direction ofspray (from top and/or bottom), the location of spray (e.g., left versusright side of part or top versus bottom side of part), the pressure atwhich fluid 22 is pumped to the nozzles 25, and the degree ofatomization, as well as other parameters such as the make-up,temperature and pH of the fluid, can be adjusted to create differentcombinations or “recipes” of these parameters in order to efficientlyand effectively remove a given type of support material 28 for a giventype of build material 35 and geometric design of additive manufacturedpart(s) 10. In some embodiments of the present invention, an operatorcan set or change these parameters using a human-machine interface(“HMI”) 38, such as a touch screen 108 connected to a general-purposecomputer having a central processing unit (“CPU”) 102. Thegeneral-purpose computer may have wired or wireless communications links105 for sending and receiving communications signals to/from componentsof the apparatus 8.

The fluid 22 is capable of dissolving and/or degrading support material28, and may be aqueous-based chemical formulations made with a singlechemical or a variety of chemicals. The fluid 22 may, in someembodiments, be referred to as a detergent. Preferably, the fluid 22,either naturally or aided by the parameter settings, degrades ordissolves support material 28 and the rough surface of the part 10without also degrading, dissolving or causing damage to the buildmaterial 35 of the part 10 that is intended to be preserved. Such fluids22 can include but are not limited to those fluids that are optimizedfor SF/SR for parts 10 made by MJ, SLA and FDM, respectively. The fluid22 can also include an anti-foaming agent to help minimize foaming ofthe fluid during the SF/SR process.

An embodiment of the present invention may be an apparatus 8 having ahousing 41 comprising a first section 44, a second section 47 arrangedadjacent to said first section 44, as illustrated in FIGS. 1, 3A, 3B,and 3C. The first section 44 may include a chamber 16 where the SF/SR ofan additive manufactured part 10 occurs. The second section 47 may housemany of the plumbing components for the apparatus 8, such as a pump 33,valves 59, and hoses 62. The second section 47 can be arranged eitherbelow or to the side of the first section 44.

The first section 44 may include a door 68 for an operator to access thechamber, and place parts 10 into and remove them from the chamber 16.The door 68 can be a counter-weighted balanced door to allow for easyaccess. As discussed further below, the chamber 16 may heat up duringthe apparatus' operation. The chamber 16 can include a ventilation orexhaust system to provide a heated equalized chamber 16 to aid both inthe removal of support material 28 as well as enhancing the evaporationof residual fluid 22 off of the part 10 upon completion of the SF/SRprocess. A ventilation system may be of any type suitable for ventingheat and vapors that can build up in the chamber 16. As one example, theventilation system may comprise one or more blowers 75 pulling air fromthe chamber 16, such as blowers rated, for example, at 0.5 to 1000 cubicfeet per minute (CFM). In this approach the ventilation system maycreate a negative pressure in the chamber 16 so that when the door 68 isopened, air is pulled inward through the door 68. In another example,the ventilation system may comprise one or more fans or blowers 75pushing air into the chamber 16, combined with a chimney or otherexhaust mechanism 78 in the roof of the chamber 16. The fan or blower 75may create a positive pressure in the chamber 16 and the chimney 78allows excess heat and vapors to escape. Additionally, windows 81 may beplaced in the sides of the chamber 16 to allow for in-process monitoringby humans and sensors of the SF/SR process.

A tray or platform 13 on which the parts 10 can be set while an SF/SRprocess occurs may be situated in the chamber 16. A first plurality ofnozzles 25 (such as the top nozzles 25A) may be arranged in the chamber16, allowing for fluid 22 to be sprayed downward toward the parts 10situated on the tray 13. A second plurality of nozzles 25 (such as thebottom nozzles 25B) may be arranged in the chamber 16, directly belowthe tray 13, allowing for fluid 22 to be sprayed upward toward the parts10 situated on the tray 13. The bottom nozzles 25B and top nozzles 25Aare thus arranged opposite from each other, spraying in directionstoward each other, with the parts 10 situated therebetween. The firstsection 44 also may include a tank 31 for holding the fluid 22. The tank31 may be situated below the bottom nozzles 25B.

The tray 13 may have openings of suitable size, quantity anddistribution, such as a mesh screen, so that the tray 13 can support theparts 10, yet allow fluid 22 to be sprayed at the parts 10 from thebottom nozzles 25B, allow fluid 22 sprayed from both the bottom and topnozzles 25B, 25A to flow down into the tank 31, and help to preventsupport material 28 that detaches from the part 10 from falling downinto the tank 31. A mesh screen 53 may be arranged between the tank 31and the bottom nozzles 25B to further prevent pieces of detached supportmaterial 28 from entering the tank 31.

In one embodiment of the invention, a first plurality of nozzles 25comprises a single spray-header of nozzles 25, and in another embodimentof the invention the first plurality of nozzles 25 comprises more than asingle spray-header of nozzles 25, such as three spray-headers of topnozzles 25A. The size of the apertures or nozzles in one spray-header ofnozzles 25 can be different from the size of the apertures or nozzles inanother spray-header, thereby resulting in different fluid velocitiesspraying from the two different sets of nozzles 25, with one velocitybeing higher than the other. For example, in the embodiment with threesets of top nozzle spray-headers 25A, the first and third sets can eachcomprise five apertures/nozzles of the same or similar size (or degreeof spray angle), while the second set can comprise threeapertures/nozzles of a larger size (or degree of spray angle). The topnozzles 25A can be either mounted to the housing 41 itself, or mountedon a movable track 42 connected to an actuator 43 that allows thenozzles 25 to oscillate in the horizontal direction. The secondplurality of nozzles 25 can be identical to the first plurality ofnozzles 25 mounted on a movable track 42 that is connected to anactuator 43, or can be stationary nozzles 25 that cannot moveindependently on a track. In one embodiment, the second plurality ofnozzles 25 comprises a spray-header having thirteen nozzles 25 each ofthe same or similar size (or degree of spray angle).

In another embodiment of the invention, nozzles 25 could be arranged tosurround the chamber 16 so that the nozzles 25 are on all six sidessurrounding the part 10 in the chamber 16. Each nozzle 25 can beindependently controlled by a separate motor or be connected as a nozzleassembly. In this embodiment there are nozzles 25 mounted bothhorizontally and vertically.

FIG. 4 depicts a further embodiment of the invention in which the bottomnozzles 25B are arranged as a U-shaped spray-header. As with theembodiment mentioned directly above, the nozzles 25 may spray the AMpart 25 from different directions and thereby spray additional sides ofthe AM part 25 more directly. In a similar manner, the top spray-headerof nozzles 25A may be U-shaped. Or, both the top spray-header of nozzles25A and the bottom spray-header of nozzles 25B may be U-shaped.

Servomotors or other actuators may be used to oscillate a spray-headerof nozzles 25 through a range of distance about a center point.Interface and control buttons may enable an operator to adjust thelocation of the center point (by causing the spray-header of nozzles 25to move forward or backward) and/or the speed at which the nozzles 25oscillate. For example, the center point could be set anywhere between arange of 0-275 millimeters and the speed could be set anywhere between arange of 0-50 mm/sec. Or, these parameters may be pre-stored inconnection with an operating recipe that the operator has the option toselect. In one embodiment of the invention the operator can also adjustthe distance that the nozzles 25 oscillate. The movement of each nozzle25 may be tracked by a position sensor. The first plurality of nozzles25 could be made to oscillate only if at least one of the valves 59 to anozzle contained in the first plurality of nozzle 25 is open. In such anembodiment, if only the second plurality of nozzles 25 is activated,then the first plurality of nozzles 25 does not oscillate.

The nozzles 25 can be individual nozzles 25, or can be tubes/pipinghaving a plurality of apertures therein, e.g. a manifold (each suchaperture is also referred to as a “nozzle”), or could include nozzles 25secured to the tubes/piping. Additionally, the individual nozzles 25,including individual nozzles secured to the tubes/piping, may beconstructed to rotate independently, using motors, in order to sprayparts 10 within the chamber 16 at a variety of angles. Each nozzle 25may be independently controlled by a separate motor or be connected toeach other so as to form a nozzle assembly. Additionally, each nozzle 25could be controlled by a multi-axis robot. The nozzles 25 may be made tomove in horizontal and/or vertical directions. It should be appreciatedthat each nozzle 25 may be connected to its own pump and plumbingsystem.

Both the first and second plurality of nozzles 25 (e.g., top and bottomnozzles 25A, 25B) may be connected to a pump 33, which may be locatedwithin the second section 47 of the housing 41. After drawing fluid 22from the tank 31, the pump 33 can force the fluid 22 through pipes 50(which may be a flexible hose) to the nozzles 25. A manifold may be usedto separate the fluid 22 output from the pump 33 into separate suppliesfor each spray-header of nozzles 25. The individual pipe 50 to eachspray-header of nozzles 25 may include a valve 59 to control the flow offluid 22 to the nozzles 25. This arrangement allows nozzles 25 to beused selectively (on/of), thereby increasing efficiency where all of thenozzles 25 are not required for SF/SR and/or where it is preferred tohave some nozzles 25 at higher or lower pressures than others.

For example, an embodiment of the invention may have one bottomspray-header of nozzles 25 and three top spray-headers of nozzles 25,where at least one of the top spray-headers has narrow-angle nozzles 25(producing comparatively higher velocity spray) and at least one of theother top spray-headers has wide-angle nozzles 25 (producingcomparatively lower velocity spray). In each of the following examples,the valve 59 controlling flow to the bottom spray-header of nozzles 25may always be open. In one mode of operation, all of the valves 59controlling flow to the top nozzles 25 can be closed so that fluid 22sprays only from the bottom spray-header 25B. This mode can produce thelowest degree of agitation of the additively manufactured parts 10 beingSF/SR processed in the chamber 16, and may be referred to as “ultra-lowagitation.” In another mode of operation the valve(s) 59 controllingflow to the top spray-header(s) 25A having wide-angle nozzles 25 may beopen, but the valve(s) 59 controlling flow to the top spray-header(s)25A having narrow-angle nozzles 25 may be closed. This mode can producea higher degree of agitation than where only the bottom nozzles 25B areused, and may be referred to as “low agitation.” In yet another mode ofoperation, the valve(s) 59 controlling flow to the top spray-header(s)25A having wide-angle nozzles 25 may be open and the valve 59controlling flow to one (but not more than one) top spray-header havingnarrow-angle nozzles 25 may be open. This mode can produce a higherdegree of agitation than the prior example, and may be referred to as“medium agitation.” In yet a further mode of operation, the valve(s) 59controlling flow to the top spray-header(s) 25A having narrow-anglenozzles 25 may be open but the valve(s) 59 controlling flow to the topspray-header(s) 25 have wide-angle nozzles 25 may be closed. This modecan produce the highest level of agitation, and may be referred to as“high agitation.” Other arrangements of spray-headers, varying sizes ofnozzles 25, and open versus closed valves 59 may be used to createadditional variations in the levels of agitation. Thus, the use of termssuch as “low,” “medium” and “high” are not meant to be limited to theprecise arrangements described in the foregoing examples, but rather toexemplify that various, relative degrees of agitation can beaccomplished as desired to meet specific needs.

An operator can use the HMI 38 to select a desired level of agitation,or the agitation level may be pre-stored in connection with a givenoperating recipe that the operator has the option to select. By settingthe agitation level, the apparatus 8 automatically opens and closes thevalves 59 to the nozzles 25 as appropriate to achieve that selectedlevel of agitation. These parameters can be set individually or byselecting a pre-stored recipe.

The pressure of the fluid 22 pumped through the system may be a functionof a variety of factors including the action of the pump 33, the length,sizing and configuration of the plumbing between the pump 33 and thenozzles 25, and the sizes and quantity of nozzles 25. The apparatus 8may have one or more sensors 65C located at or near the inlet to eachvalve 59 leading to each spray-header of nozzles 25, or at anothersuitable location, for measuring and monitoring the pressure of thefluid 22 being forced to the nozzles 25. This pressure can be, forexample, from 0.01 psi to 100 psi. During operation, the pressure canchange for a variety of reasons, and the apparatus 8 may include sensors65C for measuring the pressure. The apparatus may alert the operator ifthe pressure begins to decrease or increase from the level expected, orinitially achieved, for a given set of SF/SR processing parameters, andalso may alert the operator if the pressure drops below or exceedsminimum and maximum levels, respectively. These minimum and maximumlevels can be pre-programmed into the apparatus 8. Additionally, ifthese minimum or maximum pressure levels are exceeded, the apparatus 8can automatically shut down.

An embodiment of the invention may simultaneously achieve a high rate offluid flow through the nozzles 25, such as 5 to 150 gallons per minute,and a low pressure at which the fluid 22 is provided to the nozzles 25,such as 15-30 psi. The speed at which support material is removed may beaided by having as much flow of fluid 22 on the part 10 as possible,while protecting the build material 35 of the part 10 from erosion bymaintaining the fluid velocity below a desired level. The nozzleaperture sizes (and/or spray angles), quantities of nozzles 25 andspecifications for the pump 33 and plumbing may be selected to achievethese multiple goals. Additionally, oscillating the nozzles 25 changesthe direction and speed of the spray exiting the nozzles 25, whichprovides an additional opportunity for modulating both the force of thefluid 22 impacting the parts 10 as well as the area covered by thatfluid 22. For example, oscillating the nozzles 25 at a higher speed mayresult in a lower average force at which the fluid 22 impacts theadditive manufactured parts 10 and a wider coverage area within thechamber 16.

In another embodiment of the invention as illustrated in FIG. 5, a widerchamber 16 is used and there are two systems of top and bottom nozzles25, arranged adjacent to each other, effectively defining firstprocessing region 87 and second processing region 90 within the chamber16. In this embodiment, fluid 22 is delivered to the first processingregion 87 by the first top nozzles 25A1 and first bottom nozzles 25B1,and fluid 22 is delivered to the second processing region 90 by thesecond top nozzles 25A2 and second bottom nozzles 25B2. In thisembodiment, the tank 31 situated below the bottom nozzles 25B can be asingle tank 31 spanning the two regions 87, 90. A first pump 33A can beconnected to the first top and first bottom nozzles 25A1, 25B1, and asecond pump 33B can be connected to the second top and second bottomnozzles 25A2, 25B2. In this embodiment, the pumps 33, valves 59,spray-headers of nozzles 25, and all of the various settings relatingthereto can be set and operated in the two regions 87, 90 independently.

This embodiment enables the apparatus 8 to have different flow rates,pressures and spray velocities (i.e., agitation levels) as between thetwo regions 87, 90. This can be useful in several ways. For example,some additive manufactured parts 10 are long and have more supportmaterial 28 and/or surface areas of build material 35 toward one end ofthe part 10 (“heavy end”) versus the opposite end (“light end”). If thesame flow, pressure levels and spray velocities were applied across theentire part 10, then either the light end would be at risk forover-processing (which might include degradation or warping of the part10) or the heavy end of the part 10 would be at risk forunder-processing (leaving too much support material 28 or un-smoothedsurfaces of build material 35 remaining on the part 10). By having twoindependent SF/SR processing regions 87, 90, the part 10 can be situatedin the chamber 16 so that the end with more support material 28 and/orsurface areas of build material 35 lies in the region that has higherflow, pressure and spray velocity, while the other end of the part 10with less support material 28 and/or surfaces areas of build material 35lies in the region that has lower flow, pressure and spray velocity.This protects the second end of the part 10 from over-processing and thefirst end of the part 10 from under-processing. Another advantage ofhaving two regions is that a given part 10 may have more supportmaterial near its bottom area than near its top area. A quantity ofthese parts 10 could be simultaneously SF/SR processed with a portion ofthe quantity oriented upright in one region and the other portionoriented upside down in the other region, with each region having flowof fluid 22 and pressure appropriate for those orientations of theparts.

In an embodiment where nozzles are configured to oscillate during aSF/SR process, a motion-monitoring sensor can be used to detect which ofthe nozzles 25 are moving during the SF/SR process. The apparatus 8 mayfrequently monitor the position of the nozzles 25 and if no motion isdetected, the apparatus 8 may attempt to reset the motor controllingmovement of the nozzles 25. If a reset of the motor is unsuccessful,then the HMI 38 may alert a user and pause the SF/SR process since theapparatus 8 may not be operating properly. The detection of nozzlemovement may be done via an encoder arranged on each motor or by othersuitable means.

The tank 31 may be filled automatically with fluid 22 based onparameters set by the operator or as may be pre-stored in connectionwith a given operating recipe that the operator has the option toselect. To this end, the apparatus 8 may include devices for supplyingeach of water, support material solvent (also referred to as detergent),and anti-foaming agent supplies. Water may be supplied from a facility'swater supply 19 or from a reservoir or other storage tank. Solvent andanti-foaming agent may be supplied each from their own reservoir orstorage tank, such as a 5-gallon bucket 56 connected to the apparatus bya hose 62 or other conduit. The hose 62 for each of the solvent andanti-foaming agent may be connected to a mechanism, such as awater-powered pump, for automatically dispensing such fluids into thetank.

A liquid level sensor 65D may be situated in the tank 31 to detect thelevel of the fluid 22 in the tank 31, thereby enabling a determinationof when the fluid 22 filling the tank 31 reaches the maximum level, atwhich point the sensor 65D sends a signal that is interpreted andresults in the filling to automatically stop. The sensor 65D also may beemployed to enable detection of when the fluid 22 drops below a desiredlevel during operation, which can happen for example as fluidsevaporate, and may send a signal that is interpreted and may result inalerting the operator to use the interface to cause more fluids to bedosed into the tank (which dosing again stops automatically if themaximum fill level is reached). Alternatively, programming could beprovided to cause this dosing to occur automatically.

Use of this auto-dose feature ensures that enough fluid 22 is arrangedin the apparatus 8 for the SF/SR process to run properly. When anapparatus 8 runs for an extended period of time at high temperatures,the fluid 22 used in the SF/SR process evaporates. Also, amounts offluid 22 may adhere to interior surfaces of chamber 16 and to surfacesof components within chamber 16. In order to ensure that enough fluid 22remains in the system, a configurable desired fluid level may be set inthe software of the apparatus 8, and the fluid level in the tank 31 maybe detected using a liquid level sensor 65D such as a floating sensor todetect the liquid level. If the liquid level falls below the desiredlevel, the apparatus 8 could react by supplying additional amounts ofone or more components of the fluid 22 (e.g., water, solvent,anti-foaming agent) into the tank 31. Additionally, a configurable timeinterval could be set by a user for checking the liquid level during theSF/SR process. At the end of a configurable time interval, the SF/SRprocess may pause for an amount of time (for example, 30 seconds) inorder to let foam that may have formed in the tank 31 to settle. Oncethe settling time has elapsed, a liquid level measurement may be taken.If the liquid level has not attained the desired level, the apparatus 8may automatically add fluid to the tank 31 and in order to fill the tank31 up to the desired liquid level.

A heater 96, such as an immersion heater, and a sensor 65B for measuringtemperature, may be situated in or in connection with the tank 31.Additionally, a pH sensor 65A may be situated in or in connection withthe tank 31. The heater 96 may be used to heat the fluid 22 to a desiredtemperature and, based on feedback from the temperature sensor 65B, tomaintain the fluid 22 at that temperature. The heater 96 may be used toheat the fluid 22 to a desired temperature within an allowable range,such as for example, 85° F. to 160° F., or another process-suitablerange. The fluid 22 in the tank 31 may be heated to the desiredtemperature prior to starting the SF/SR process to spray the parts 10,or the fluid 22 can be used before it is heated at all or when it isonly partially heated to the desired temperature. In this latterapproach, the SF/SR process begins with the fluid 22 at a lowtemperature and, as time elapses during the SF/SR process, the heater 96operates to increase the temperature of the fluid 22 to the desiredlevel. The approach of gradually increasing the temperature of the fluid22 can aid in the removal of support material 28. This is because thefluid 22 can usually remove support material 28 over a range oftemperatures. Thus, by engaging in SF/SR as the fluid temperature rises,the fluid 22 can begin to remove support material 28 as the fluid 22reaches the lowest temperature suitable for removing support material 28and then remove the support material 28 more rapidly as the fluidapproaches the final desired temperature. In this manner, the buildmaterial 35 of the part 10 will not heat up as much as compared to thecase where the fluid 22 is at the highest temperature from the start ofthe SF/SR process. This helps to protect the build material 35 of thepart 10 from degradation, such as warping.

The pH sensor 65A can detect the pH of the fluid 22, which at the outsetcan be a reflection of the combination of liquids forming the fluid 22(e.g., solvent, water and, if used, anti-foaming agent) and may be usedwhile filling the tank 31 to achieve the desired pH. The pH can changeduring the apparatus' 8 operation, for example due to dissolved supportmaterial 28 contaminating the fluid 22 or due to evaporation of portionsof the fluid 22. The pH sensor 65A may be used to detect such changesand to alert the operator when the pH drops below or exceeds a desiredlevel, whereupon the operator may use the HMI 38 to cause dosing offluids as needed to adjust the pH to the desired level. For example, ifthe pH is too high (i.e., too basic), then more solvent can be added.But if the pH is too low (i.e., too acidic), then more water can beadded. Alternatively, the apparatus 8 may be configured to automaticallydose fluids as needed to adjust the pH. The desired temperature and pHmay be set by the operator using the HMI 38, or may be pre-stored inconnection with a given operating recipe that the operator has theoption to select.

As the fluid 22 flows through the apparatus 8, its temperature canchange, which may be undesirable. In particular, it is important tomaintain the fluid 22 at the desired temperature as it travels from thetank 31 to the nozzles 25. Yet, many pumps 33 heat up while they areoperating and transfer that heat to the fluid 22 as it moves through thepump 33. In embodiments of the present invention, it is preferable touse a pump 33 that adds minimal heat to the fluid 22, such as amagnetically coupled pump 33.

Atomization of the fluid 22 by spraying it through appropriately sizednozzles 25, where the fluid 22 separates into small droplets while alsospreading out in a flat fan, hollow cone, or full cone spray patternhelps to control the force at which fluid 22 impacts the part 10 whilemaximizing flow of the fluid 22. The top nozzles 25A may be further awayfrom the parts 10 being SF/SR processed than the bottom nozzles 25B, andin such a configuration, the force of the spray from the top nozzles 25Aas it impacts the parts 10 can sometimes fall below a desired amount.The design of the bottom nozzles 25B can help with this. The spray fromthe bottom nozzles 25B may have enough force to hit the bottom of theparts 10 and then continue to travel upwards to heights above the parts10. There, the droplets combine with each other and/or droplets from thetop nozzles 25A into larger droplets, whereupon these larger dropletsfall down onto the parts 10. Aided by both gravity and the force of thedrops from the top spray nozzles 25A, these larger particles may hit theparts 10 with more flow and kinetic energy than drops coming from thetop nozzles 25A alone or the bottom nozzles 25B alone. Nonetheless, thetop nozzles 25A may be mounted in a way so as to be adjustable closer toor further away from the parts 10. Likewise, the location of the parts10 may be adjustable such that parts 10 are set further away from thebottom nozzles 25B and thus closer to the top nozzles 25A, orvice-versa.

The fluid 22 in the tank 31 may be drained automatically. At the end ofeach SF/SR process, there may be the option to drain all the fluid 22from the tank 31 and replace it with new fluid 22. This option may bepre-set by the operator or selected by the operator upon the completionof an SF/SR process. An auto-drain feature may also be used to drain thetank 31 after a prescribed number of SF/SR processes, which may be setby the operator.

After the tank 31 is drained, the tank 31 may be automatically filledwith clean water, and used for rinsing the part 10 in order to removefluid 22 remaining on the part 10. The water may be heated in the samemanner as the fluid 22. When selecting the parameters for the SF/SRprocess, the operator may set the temperature for the rinsing water orselect the temperature from a pre-stored recipe. In one embodiment, thefluid 22 for removing support material 28 may be automatically drainedfrom the tank 31 after the designated run time and replaced with cleanwater (using the same auto-fill mechanisms described above), which isthen cycled through the apparatus 8 to rinse the parts 10, at the sameagitation level setting as used during the support removal portion ofthe SF/SR process. During this rinsing process, the water may bepre-heated to the desired temperature or the temperature may begradually raised while the apparatus is running.

During the SF/SR process, heat from the fluid 22 in the tank 31 can heatup air in the chamber 16. This heated air in the chamber helps, in turn,to maintain the fluid 22 at the desired temperature while fluid 22 issprayed from the nozzles 25 and collects back into the tank 31. At theend of a SF/SR and/or rinse cycle, the heater 96 in the tank 31 may bekept operating to maintain the heat in the chamber 16, which, in turn,may be useful for drying the parts 10 prior to removing them from thechamber 16. When carried out in this manner, an SF/SR process may besaid to be a “dry-to-dry” process: that is the parts 10 placed in thechamber 16 are dry and do not require preparation work to be done onthem prior to the SF/SR process, and the parts 10 come out of thechamber 16 dry after the SF/SR process is complete.

Operation. A method according to the present invention, illustrated inFIG. 6, may comprise the following of steps to remove support material28 and/or finish a surface of build material 35 of a part 10 and rinseresidual material from a part 10 made using additive manufacturing. Theoperator may use 200 the HM 38 to cause the tank 31 to fill with fluid22. The operator also may use the HMI 38 to set other SF/SR processingparameters for the additive manufactured parts 10 to be SF/SR processed,including temperature (of both the support removal and rinsing fluids),pH of the fluid 22, the length of run time (in hours and minutes),agitation level (e.g., ultra-low, low, medium or high agitation),center-point position of the top spray-header(s) of nozzles 25, therange of distance through which the top nozzles 25A oscillate, and thespeed of oscillation of the top nozzles 25A. Additionally, the operatormay place 203 one or more additive manufactured parts 10 on the tray 13within the chamber 16. The heater 96 in the tank 31 may operate to heatthe fluid 22, which in turn helps to heat the air in the chamber 16. Thefluid 22 can be brought to full temperature prior to starting the SF/SRprocess, or gradually after the SF/SR process begins.

Next, the pump(s) 33 may activate, drawing fluid 22 from the tank 31,through the pump(s) 33, and then forcing 206 the fluid 22 through themanifold (if used) and those of the open valves 59 toward and throughthe nozzles 25 associated with the open valves 59 in order to spray thefluid 22. The upper nozzles 25A may oscillate when the associated valves59 are open and allow fluid 22 to flow to the nozzles 25A, and thosenozzles 25A may rotate or otherwise move in accordance with the selectedsettings. The fluid 22 then exits the nozzles 25 as atomized and/orsemi-atomized fluid 22 and collides with the part 10, including thesupport material 28, whereupon the support material 28 begins todissolve or otherwise separate from the part 10 and/or rough surfaces ofbuild material 35 of the part begin to smooth. The fluid 22 then passesthrough the openings in the tray 13 and collects 209 in the tank 31located under the bottom nozzles 25B, whereupon the fluid 22 cycles 206through the nozzles 25 again as the pump 33 continues to draw fluid 22from tank 31. This cycling 212 of the fluid 22 continues for theduration of the run time set by the operator or until the operatormanually stops the SF/SR process.

During the SF/SR process, the apparatus 8 may measure the fluid level inthe tank 31 to ensure enough fluid 22 is contained in the tank 31. Ifthere is not enough fluid 22 in the tank 31 (e.g., due to evaporation)the apparatus 8 may add fluid 22 components, such as the water, solventand/or anti-foaming agent as appropriate. The apparatus 8 also maymeasure the pH of the fluid 22 and dose the tank 31 with water and/orsolvent as needed to maintain the desired pH level.

After the prescribed amount of time, the spraying stops, the fluid 22may automatically drain 215 from the tank 31, the tank 31 mayautomatically fill 215 with clean water, and then the spraying mayre-start to rinse the parts 10. The water may be cycled 218 through thesystem until a prescribed amount of time has elapsed, the rinsingprocess stops, and the parts 10 may remain in the chamber 16 for dryingby the heated air in the chamber 16.

The ventilation system may operate during the SF/SR process to safelyexhaust excess vapors and thus prevent them from escaping out of thechamber 16 to areas that could pose a threat to users standing aroundthe apparatus 8 while the SF/SR process is occurring. The ventilationsystem may be kept running for a time interval (for example, 5 minutes)after an SF/SR process is completed.

The method may be carried out so as to determine the agitation level inconcert with optimal temperature in order to maximize the speed andefficiency of SF/SR processing. When the fluid 22 is too cool, thesupport material 28 may not be removed as efficiently, but when thefluid is too hot, the part can experience damage such as shapedegradation, including warpage. Additionally, as will be appreciated bythe disclosure herein, the hardware, electronics, software and fluid 22may work together to provide desired levels of efficacy and efficiency,from delicate support removal to more robust removal with higherthroughput.

Settable parameters can be different and/or customized for particularbuild and support materials 35, 28 out of which the additivemanufactured parts 10 are made, the part geometries including thegeometries of support structures, and the degree and speed of supportmaterial removal desired. Balancing and varying these parametersincreases the efficacy and efficiency at which support material 28 canbe removed. The apparatus 8 can be pre-programmed at a factory with“recipes” of the parameter settings known to be suitable for varioussupport and build materials 28, 35, part geometries, etc. Thus, by asingle activation operation, e.g. pressing one button or a shortsequence of buttons, the operator may be able to set all of theparameters for a given SF/SR process. Additionally, the operator can setparameters and save them as a recipe, which the operator can then selectin the future rather than re-inputting each of the settings.

The present invention may further include a logic controller 99 tomonitor communication between a central processing unit (“CPU”) 102 andthe HMI 38. In such an embodiment of the invention, a signal may be sentfrom the HMI 38 to the CPU 102, and vice-versa. The logic controller 99may monitor this signal to make sure the signal changes during the SF/SRprocess. If the signal stops, the logic controller 99 may react byeither shutting down the apparatus 8, or the HMI 38 will inform theoperator to restart the apparatus 8. The HMI 38 and CPU 102 may beconnected to the Internet in order to be operated and evaluatedremotely. Additionally, this Internet connection could enable the use ofa database that contains a plurality of test parameters and additionalrecipes that may be used to optimize the SF/SR and rinse processes. Thedatabase may alternatively be contained on a hard drive that may beassociated with the apparatus 8 itself and be uploaded periodically to aremotely located storage device.

The apparatus 8 may collect and store data about settings and about howthe apparatus 8 should or does operate, which can be used to service theapparatus 8 and as feedback for improving SF/SR settings for varioustypes of support and build materials 28, 35 and part geometries.

In the foregoing description, example embodiments are described. Thespecification and drawings are accordingly to be regarded in anillustrative rather than a restrictive sense.

It will be appreciated that various aspects of the above-disclosedinvention and other features and functions, or alternatives thereof, maybe desirably combined into many other different systems or applications.Various presently unforeseen or unanticipated alternatives,modifications, variations, and/or improvements therein may besubsequently made by those skilled in the art, and those alternatives,modifications, variations, and/or improvements are intended to beencompassed by the following claims.

Although the present invention has been described with respect to one ormore particular embodiments, it will be understood that otherembodiments of the present invention may be made without departing fromthe spirit and scope of the present invention. Hence, the presentinvention is deemed limited only by the appended claims and thereasonable interpretation thereof.

1. An apparatus for removing support material from and/or smoothingsurfaces of an additively manufactured part, comprising: a chamber; asupport surface within the chamber, and configured to support anadditively manufactured part (the “AM part”); and one or more nozzleswithin the chamber, and configured for spraying a fluid at said AM part,wherein said nozzles generate an atomized or semi-atomized spray of saidfluid.
 2. The apparatus of claim 1, further comprising a tank configuredto hold a volume of said fluid, and positioned to capture the fluidafter the fluid is sprayed.
 3. The apparatus of claim 2, furthercomprising a heater at least partially within said tank for heating saidfluid to a desired temperature.
 4. The apparatus of claim 1, whereinsaid support surface further comprises openings sized and configured toallow said fluid to pass through said one or more openings.
 5. Theapparatus of claim 1, wherein the nozzles are arranged as twospray-headers of nozzles.
 6. The apparatus of claim 5, furthercomprising: a first spray-header of nozzles configured to spray saidfluid substantially downward toward the AM part; and a secondspray-header of nozzles configured to spray said fluid substantiallyupward toward the AM part.
 7. The apparatus of claim 6, wherein one orboth of said first and second spray-headers of nozzles is connecteddirectly or indirectly to an actuator for translating said spray-headerof nozzles back and forth in a planar motion.
 8. The apparatus of claim6, wherein one or both of said first and second spray-headers of nozzlesis secured to a mount that is adjustable to move the spray-header nearerto or further away from said support surface.
 9. The apparatus of claim8, wherein one or both of said first and second spray-headers of nozzlesis connected directly or indirectly to an actuator for translating saidspray-header of nozzles back and forth in a planar motion.
 10. Theapparatus of claim 6, wherein nozzles of the first spray-header ofnozzles are of two or more sizes.
 11. The apparatus of claim 10, whereinfluid can flow to spray through first nozzles of one size at the sametime that fluid cannot flow to spray through second nozzles of a secondsize.
 12. The apparatus of claim 6, wherein nozzles of the secondspray-header of nozzles are of two or more sizes.
 13. The apparatus ofclaim 6, wherein nozzles of the first spray-header of nozzles are of twoor more sizes and nozzles of the second spray-header of nozzles are oftwo or more sizes.
 14. The apparatus of claim 13, wherein fluid can flowto spray through first nozzles of one size at the same time that fluidcannot flow to spray through second nozzles of a second size.
 15. Theapparatus of claim 14, wherein both of the first and second nozzles areassociated with the first spray-header of nozzles.
 16. The apparatus ofclaim 14, wherein the first nozzles are associated with the firstspray-header of nozzles and the second nozzles are associated with thesecond spray-header of nozzles.
 17. The apparatus of claim 1, furthercomprising a blower for forcing air into or pulling air out of thechamber.
 18. The apparatus of claim 1, further comprising a vent forallowing air to leave the chamber.
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 30. Anapparatus for removing support material from or smoothing surfaces of anadditively manufactured part, comprising: a chamber; a support surfacewithin the chamber, and configured to support an additively manufacturedpart; one or more nozzles within the chamber, and configured forspraying a fluid at said AM part, wherein said nozzles generate anatomized or semi-atomized spray of said fluid; and an HMI adapted forselection of a desired level of agitation by opening and closing valvesto the one or more nozzles.
 31. An apparatus for removing supportmaterial from or smoothing surfaces of an additively manufactured part,comprising: a chamber; a support surface within the chamber, andconfigured to support an additively manufactured part; one or morenozzles within the chamber, and configured for spraying a fluid at saidAM part, wherein said nozzles generate an atomized or semi-atomizedspray of said fluid; and one or more sensors located at or near an inletto the one or more nozzles for monitoring pressure.